A burner embodied as a pilot burner having an igniter and ignition electrodes leading to the igniter is described in EP 0 193 838 B1, for example. The igniter has the task of igniting the fuel. The ignition electrodes are fixed on the exterior of the pilot burner and run parallel to its longitudinal axis. The fuel supply is located in the interior of the pilot burner and ends in fuel outlet openings. The ignition electrodes end in the area of the fuel outlet openings and ignite the fuel exiting there by means of an ignition spark. The ignition spark is generated by means of an ignition voltage applied between two ignition electrodes and is present for the entire duration of the ignition.
If one or both of the ignition electrodes mounted on the pilot burner are damaged or bent during transportation or installation, this can have a negative effect on the operational reliability of the ignition electrodes. Damage or bending can therefore make it become necessary to replace the ignition electrodes.
Replacing the ignition electrodes can also become necessary if one of the electrodes is bent to such an extent that a current sparkover occurs between an electrode lead and another metallic component instead of between the electrode tips and consequently the gas mixture cannot be ignited.
U.S. Pat. Nos. 2,850,084, 5,860,804 and 5,865,651 essentially disclose igniters having ignition electrodes in which the ignition is brought about by the heating of an ignition electrode as a consequence of its high resistance, which is to say thermally. This form of ignition is referred to in the following as thermal ignition. The possibility of an electronic or electric ignition, by sparkover for example, is mentioned only in U.S. Pat. No. 5,860,804.
Various protective elements or protective enclosures for protecting the ignition electrode area in proximity to which the ignition takes place are disclosed in U.S. Pat. Nos. 2,850,084, 5,860,804 and 5,865,651. Said protective enclosures are characterized in that they can extend into the resulting flame and are intended to protect the ignition electrodes in the ignition zone in particular against possible soiling or damage. In this arrangement the areas of the ignition electrodes which are adjacent to the ignition zone, i.e. which lead to or away from the ignition zone, are not protected by a corresponding protective element.
Igniters having ignition electrodes are also described in U.S. Pat. Nos. 4,029,936, 6,777,650 B1 and 3,823,345. In these, at least areas of the ignition electrodes which are adjacent to the ignition zone, i.e. which lead to or away from the ignition zone, are also enclosed, at any rate partially, by a housing. However, these igniters are exclusively thermal igniters. Furthermore, these igniters are not igniters for gas turbine burners. No gas turbine burners are in fact disclosed in U.S. Pat. Nos. 2,850,084, 5,860,804, 5,865,651, 4,029,936, 6,777,650 B1 and 3,823,345. However, the ignition electrodes that are used in the context of gas turbine burners and ignite with the aid of an ignition spark are adversely affected considerably more easily in their operational reliability by comparison with ignition electrodes of thermal igniters.